I. Field of the Invention:
The present invention relates to a frame used in the production of printed circuit boards. More particularly, the present invention relates to a frame for aligning and securely retaining two glass masters and a substrate upon which printing will be done.
II. Description of the Prior Art:
In conjunction with recent advances in photograph, graphics and printed circuit board arts, a variety of devices for retaining and aligning master patterns with surfaces for printing have been developed. Such devices include those shown in U.S. Pat. No. 4,525,061 dated June 25, 1985 to Toshiro Oki; U.S. Pat. No. 4,582,422 dated Apr. 15, 1986 to Edward J. Stroud; U.S. Pat. No. 4,494,867, 3,762,816 and 3,645,612 to Joseph H. Wally, Jr. which are dated Jan. 22, 1985, Oct. 2, 1973 and Feb. 29, 1972 respectively; U.S. Pat. No. 4,423,954 dated Jan. 3, 1984 to Ezio Curti; and U.S. Pat. No. 3,695,760 dated Oct. 3, 1972 to Alexander L. Orr. One of the coinventor's (i.e. S. A. Brown) earlier U.S. Pat. No. 3,199,430 dated Aug. 10, 1965 also relates to frame for aligning printing elements in exact registry with one another to photographically reproduce images on opposite sides of a sheet of light sensitive material.
A real problem relating to the manufacture of printed circuits arises from the competing desires for speed and accuracy. The systems generally used today either are too time consuming to use so that the cost of the resulting products is inordinately high or too inaccurate so that many of the products are rejected. Hence, there is a real need in the art for a frame used in the manufacture of printed circuits which is fast and accurate, and, thus, more reliable and efficient than the frames which are commercially available today.